Compact annular field imager optical interconnect

ABSTRACT

The present disclosure provides an optoelectronic module. In one aspect, the optoelectronic module includes an insertion member including a housing insert and an imager disposed in the housing insert, and a receiving member including an interposer, a housing disposed on the interposer, and an optoelectronic device electrically connected to said interposer. The housing of the receiving member is configured to engage and receive the housing insert of the insertion member. The optoelectronic device of the receiving member is configured to align with the imager of the insertion member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/532,116, filed on Aug. 5, 2019, entitled COMPACT ANNULAR FIELD IMAGEROPTICAL INTERCONNECT, which is a continuation of U.S. application Ser.No. 14/213,014, filed on Mar. 14, 2014, entitled LOW PROFILE OPTICALINTERCONNECT, now U.S. patent Ser. No. 10/373,998, issued on Aug. 6,2019, which claims priority to U.S. Provisional Applications Nos.61/792,886, filed Mar. 15, 2013 and 61/783,507, filed Mar. 14, 2013, theentire contents of all of which are incorporated herein by reference andfor all purposes.

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with U.S. Government support from the U.S. Armyunder Contract W31P4Q-09-D-0004. The U.S. Government has certain rightsin the invention.

BACKGROUND

These teachings generally relate to optical interconnects and signalrouting.

Current signal routing from one circuit board to another within anelectronics enclosure typically uses an electrical path through a commonbackplane and backplane connectors. Routing signals through thebackplane is often difficult on densely populated circuit boards andlimits layout freedom.

There is a need for a signal routing solution that frees board layoutand reduces the number of connections to the backplane and traces run tothe backplane.

SUMMARY

Various embodiments of the present teachings disclose optoelectronicmodules that reduce the need to route signals through connectors or tothe backplane by routing signals optically between boards.

For a better understanding of the present invention, together with otherand further objects thereof, reference is made to the accompanyingdrawings and a detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a relay lens system as used in these teachings.

FIG. 2 illustrates an embodiment of the modules of these teachings asmounted on two adjacent boards.

FIG. 3 shows embodiments of (a) an emitter die and (b) a detector die inthese teachings.

FIG. 4 shows an embodiment of the detector die in these teachings withthe wirebonds attached.

FIG. 5 shows embodiments of various imagers in these teachings.

FIG. 6 shows embodiments of detector dies with different variations ondetector element size and number in these teachings.

FIG. 7 illustrates an embodiment of the optical system in theseteachings.

FIG. 8 shows an embodiment of the module in these teachings.

FIG. 9 shows another embodiment of the module in these teachings.

FIG. 10 shows the embodiment of the module illustrated in FIG. 8 withthe housing transparent to show a wirebond protection feature of theseteachings.

FIG. 11 shows an exploded view of the embodiment of the module of theseteachings illustrated in FIG. 8.

FIG. 12 shows a molded-housing embodiment of the module of theseteachings.

FIG. 13 shows an embodiment of the directly board-mounted module ofthese teachings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is made to FIG. 1, which illustrates an imaging relay lenssystem 11 including a pair of lenses 10 and 12 used to reimage an objectarray 16 to an image array 14. See, for example, U.S. Pat. Nos.6,635,861, 7,015,454, 7,446,298, and 8,171,625, which are incorporatedherein by reference in their entirety and for all purposes.

The system 11 in FIG. 1 is designed to substantially toleratemisalignments between a first imager assembly 2 (comprising a housing 6,an imager 12, and an object array 16), and a second imager assembly 4(comprising a housing 8, an imager 10, and an image array 14), making aconnectorless opto-electronic data transmission scheme possible. Thefirst imager assembly 2 and the second imager assembly 4 are each hereinreferred to as a “module,” which refers to an assembly or component thatcontains, but is not limited to, a housing, an imager, and an image orobject array. An array may include optoelectronic components,waveguides, or other sources of electromagnetic radiation, or detectorsof electromagnetic radiation. The object array 16 includes a singleemitter or an array of emitters, and the image array 14 includes asingle detector or an array of detectors. Herein, “emitter” refers to asource of light including, but not limited to, VCSELs, LEDs, opticalfibers, and optical waveguides. Herein, a “detector” refers to a targetfor said light, including, but not limited to, waveguides, photodiodes,optical fibers, and optical to electrical converters. Herein, an“imager” refers to an optical device or element capable of substantiallytransmitting light emitted by a source, such as but not limited to arefractive lens, a gradient index (GRIN) rod, a reflective opticalassembly, a diffractive lens, etc.

In operation, electromagnetic radiation (typically in the ultraviolet,visible, and/or infrared bands, herein referred to generally as light)emitted or reflected by a given object (either real or virtual, hereinreferred to generally as emitters) located at the object plane (in thisembodiment, but not limited to, an object array 16) is incident on afirst imager 12, in this embodiment, comprising, but not limited to, agradient index (GRIN) rod lens, which is capable of substantiallyreceiving a portion of the light emanating from the object array 16 andsubstantially collimating the light. The light is then incident on asecond imager 10, in this embodiment, comprising, but not limited to, agradient index (GRIN) rod lens, which is capable of substantiallyreceiving the light from the first imager 12 and substantially focusingthe light to a image array 14. The first imager 12 and second imager 10are affixed to housings 6 and 8 respectively.

Reference is made to FIG. 2, wherein an embodiment of an optical system20 is shown, where the first imager assembly 2 and second imagerassembly 4 are embodied as modules 24 and 25, acting together inconnectorless pairs of Optical Data Pipes (ODPs). ODPs transmit datafrom a first circuit board 18 to a second circuit board 22 directlywithout the need to route signals through connectors on a commonbackplane and without the need for any common electrical or mechanicalconnection of the circuit boards 18 and 22 provided the ODP modules areoriented and positioned within the acceptable relative misalignmentdetermined by the imager and array designs. In various embodiments, theODP modules 24 and 25 may be a transmitter module, a receiver module, ora bi-directional transceiver module, depending on design choices. Thesemodules can be electrically connected to the mounts or circuit boards 18and 22, and operated as discrete opto-electronic devices.

Reference is made to FIG. 3(a) which illustrates an embodiment of theobject array 16 as illustrated in FIG. 1, comprising an optoelectronictransmitter die 36 including an array of emitters 44 (shown as an arrayof small circles) and an array of wirebond pads 38 (shown as an array ofsmall squares). Reference is made to FIG. 3(b) which illustrates anembodiment of the image array 14 as illustrated in FIG. 1, comprising anoptoelectronic receiving die 32 including an array of detectors 42(shown as an array of large circles) and an array of wirebond pads 38(shown as an array of small squares).

Reference is made to FIG. 4, which illustrates the image array 32illustrated in FIG. 3b , where the receiving die 32 is electricallyconnected with an interposer (not shown) by means of wire bonds 46,connected to the array of wirebond pads 38 on the die 32. The array ofwire bond pads 38 are shown merely for exemplary purposes and not forlimiting the arrangement. Alternative means are possible to electricallyconnect the die with the interposer using, for example, flip chiptechnology.

Reference is made to FIG. 5, which illustrates a comparison of relativesizes according to related embodiments. Two embodiments of advancedimagers 52 and 54 are shown alongside a Gradient Index (GRIN) lens 48,where FIG. 5(a) illustrates the GRIN lens 48 with a die 32 (the same dieas in FIG. 4), FIG. 5(b) illustrates amore compact imager 52 with a die32, and FIG. 5(c) illustrates an even smaller imager 54 with a die 56having an array with a reduced number of emitters or detectors (hereinreferred to generally as channels). Further details regarding theadvanced imager options are illustrated in FIG. 6(a), where compactimager 52 is above an array of detectors 42 on die 32 illustrated inFIG. 3b . The smaller imager 54 can be used by reducing the number ofdetectors 42, as shown in FIG. 6(b) on the die with fewer channels 56,or by maintaining the number of channels (and detectors) but usingreduced-size detectors 58 on die 62 as shown in FIG. 6(c).

A schematic view of a compact annular field imaging relay lens 70 isprovided in FIG. 7 with an optical ray trace shown for a pair of objectelements within the annular field. In operation, light originating froma first source element 64 in an annular source array 71 is incident upona first half relay lens 73 comprising a catadioptric element where thelight is refracted by a first optical surface 74, which is substantiallycapable of receiving a portion of the light, and substantiallytransmitted to a first reflective surface 66, which is substantiallycapable of receiving the light refracted by the first optical surface74. The light is then reflected by the first reflective surface 66 andtransmitted to a second reflective surface 68, which is capable ofsubstantially receiving the light reflected by the first reflectivesurface 66. The light is then reflected by the second reflective surface68 and transmitted to a second optical surface 82, which issubstantially capable of receiving the light reflected by the secondreflective surface 68, where the light is refracted and transmittedtowards a second half relay lens 83, which is oriented substantiallysymmetric to the first half relay lens 73 about the plane 81 separatingthe two lenses 73 and 83.

The light is then incident upon the second half relay lens 83 comprisinga catadioptric element where it is refracted by a first optical surface82, which is substantially capable of receiving the light, andsubstantially transmitted to a first reflective surface 88, which issubstantially capable of receiving the light refracted by the firstoptical surface 82. The light is then reflected by the first reflectivesurface 68 and transmitted to a second reflective surface 66, which issubstantially capable of receiving the light reflected by the firstreflective surface 68. The light is then reflected by the secondreflective surface 66 and transmitted to a second optical surface 74,which is substantially capable of receiving the light reflected by thesecond reflective surface 66, where it is refracted and imaged to afirst detecting element 86 in an annular detecting array 91.

In a similar fashion, a second source element 84 in the annular sourcearray 71 is substantially reimaged by the pair of compact annular fieldimaging relay lenses 73 and 83 to a second detecting element 88 in theannular detecting array 91, and likewise all source elements in theannular source array 71 are substantially reimaged to respectivedetecting elements in the annular detecting array 91. In practice, thehalf relay lenses 73 and 83 can include any combination of refractive,reflective, or catadioptric elements.

FIG. 8 shows an ODP module 80 in accordance with an embodiment of thepresent disclosure. As shown in FIG. 8, ODP module 80 includes an imager96, which is capable of substantially focusing light onto an array ofdetectors on an optoelectronic die 108, substantially collimating lightemitted from an array of emitters on an optoelectronic die 108, or anycombination thereof (including bi-directionally focusing and collimatinglight between arrays including both detectors and emitters); an imagerhousing 116 (in this embodiment, comprising an imager housing base 98and an imager housing insert 94) to position, hold and protect theimager 96, and provide protection for the opto-electronic die 108 andwire bonds 112; an optoelectronic die 108 with an array of detectors,emitters, or both; and an interposer 102.

In this embodiment, the interposer 102 is a printed circuit board. It isappreciated that in other instances, interposer 102 may be, for example,a thick film ceramic circuit card, a co-fired ceramic circuit card, orany substrate capable of routing electrical signals. In this embodimentthe die 108 is electrically connected by, but not limited to, wire-bonds112 to the interposer 102 and affixed with epoxy 104. The imager isaffixed with epoxy 114 within the imager housing 116 and the imagerhousing 118 in turn is affixed to the interposer 102. In otherembodiments, components affixed to each other with epoxy may be affixedby other means, including, but not limited to, heat staking, molding,crimping, pressing, and welding.

FIG. 9 shows the module 80 of FIG. 8 as being mounted to an applicationcircuit board 118. This particular embodiment 90 has the followingfeatures: an imager 96 is recessed from the front surface of the imagerhousing 124 to prevent damage to the imager 96, should the two opposingODP modules 90 contact each other because of flexing of the applicationPCBs or for some other reason; a two-piece housing where the imagerhousing insert 94 is threaded into the imager housing base 98 to providea focus adjustment during initial alignment.

In this embodiment 90, the interposer 102 substantially conductselectrical signals between the optoelectronic die 108 and the circuitboard 118 on which interposer 102 is mounted via surface mounttechnology, in this case for example, but not limited to, a Land GridArray 106 (called out in FIG. 8, but too thin to be seen in thissection) or Ball Grid Array. Other surface mount technologies that couldbe used include, but are not limited to, column grid arrays, micro-ballgrid arrays, and Low-profile Quad Flat Package (LQFP). The module 80 canhave other means of electrical connection such as but not limited todiscrete wires, flexible printed circuits, or pin arrays. The module 80can also be mounted to substrates other than printed circuit boards, andcan be mechanically affixed to the substrate with an epoxy 122 as shownin FIG. 9, or by another means such as, but not limited to, heatstaking, welding, or soldering.

Other embodiments include, but are not limited to, the previously listedembodiment 80 with substitutions such as, but not limited to, any or allof the following: a flip-chip die instead of a wire-bonded die 108; asingle-piece or multi-piece housing, instead of a two-piece housing 116;and a through-hole pin array, any surface mount technology, orwire-bonds for electrically connecting to the application circuit boardor mount instead of using a land grid or ball grid array.

Further, as shown in FIG. 10, a partially transparent view of theembodiment 80 shown in FIG. 8, and, as shown in FIG. 11, an explodedview of the embodiment 90 shown in FIG. 9, a means of allowing forin-plane alignment of the imager 96 to the object array or image array(in this embodiment an optoelectronic die 108) can limit travelsufficiently to prevent damage to the wire-bonds during the alignmentprocess. The wirebond protection is embodied in the posts 128 on theimager housing base 98 and oversized notches 126 in the interposer 102that accept the posts 128. When the posts 128 hit the sides of thenotches 126, as illustrated in FIG. 10, the housing 116 has reached thelimit of its travel. Yet another embodiment includes an imager/housingassembly that incorporates datum geometry that substantially fixes theimager in the correct location with respect to the emitter/detectorarray.

FIG. 12 shows an embodiment of a module of these teachings 120 that hasan injection-molded housing 132 molded around the imager 138. Once theimager 138 is focused and aligned to the die 108, the housing 132 andinterposer 142 can be bonded together.

In another embodiment of a module of these teachings, as shown in FIG.13, an ODP module 130 includes a die mounted and wire bonded directly tothe application circuit board 118, with the interposer being eliminated.The housing 116, in turn, is bonded directly to the application circuitboard 118. The bonded assembly of the housing 116 and imager 96 can beactively aligned to the board-mounted die, or placed in a datum geometrythat substantially fixes the bonded housing 116 and imager 96 assemblyin the correct location with respect to the object array, image array,or any combination thereof.

Note that while housings discussed herein are shown as part of theimager and housing assemblies, the functions performed by the housings(for example, but not limited to, protection, mounting features, andtooling features) can be incorporated into the imagers. Herein, wherethe term “housing” is used to refer to the component or componentscontaining or holding an imager, it should be taken to also mean thosefeatures on an integrated housing-imager, such as, but not limited to, amolded optical element with housing features that serve the samepurpose.

Note that herein, “transmitting elements”, also known as “transmitters”and “emitters,” can refer to any number of devices, such as but notlimited to, optical waveguides, optical fibers, and VCSELS. Herein,“receiving elements,” also known as “receivers,” can refer to any numberof devices, such as, but not limited to, optical waveguides, opticalfibers, and optoelectronic detectors. The term “optoelectronicdetectors” (or simply “detectors”) refers to elements that produce anelectrical signal in response to incident light.

As used herein, the singular forms “a,” “an” and “the” include theplural reference unless the context clearly dictates otherwise. Exceptwhere otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.”

For the purpose of better describing and defining the present invention,it is noted that terms of degree (e.g., “substantially”, “about,” andthe like) may be used in the specification and/or in the claims. Suchterms of degree are utilized herein to represent the inherent degree ofuncertainty that may be attributed to any quantitative comparison,value, measurement, and/or other representation. The terms of degree mayalso be utilized herein to represent the degree by which a quantitativerepresentation may vary (e.g., ±10%) from a stated reference withoutresulting in a change in the basic function of the subject matter atissue.

Although embodiments of the present teachings have been described indetail, it is to be understood that such embodiments are described forexemplary and illustrative purposes only. Various changes and/ormodifications may be made by those skilled in the relevant art withoutdeparting from the spirit and scope of the present disclosure as definedin the appended claims.

What is claimed is:
 1. A system comprising: an imager; said imagerhaving an optical axis; an array of at least two optoelectronic devicescomprising at least one emitter or detector; said array of at least twooptoelectronic devices being located in an annular region substantiallycentered about said optical axis; said array of at least twooptoelectronic devices being mounted to a circuit board; said imageroptically operatively connected to said array of at least twooptoelectronic devices.
 2. The system of claim 1 further comprising ahousing: said housing configured to mount said imager on said circuitboard; said housing further configured to align said imager to array ofat least two optoelectronic devices.
 3. The system of claim 1 whereinthe circuit board is an interposer.
 4. The system of claim 1 wherein thecircuit board is an interposer.
 5. An optoelectronic module comprising:an array of at least two electrical connections; an imager, said imagerhaving an optical axis; an array of at least two optoelectronic devicescomprising at least one emitter or detector; said array of at least twooptoelectronic devices being located in an annular region substantiallycentered about said optical axis; said array of at least two electricalcontacts operatively electrically connected to said array of at leasttwo optoelectronic devices; said array of at least two optoelectronicdevices being optically operatively connected to said imager.
 6. Theoptoelectronic module of claim 5 wherein the said array of at least twoelectrical connections is a land grid array.
 7. The optoelectronicmodule of claim 5 wherein the said array of at least two electricalconnections is a ball grid array.
 8. The optoelectronic module of claim5 wherein the said array of at least two electrical connections is a pinarray.
 9. The optoelectronic module of claim 5 further comprising ahousing; said housing configured to align the said imager to said arrayof at least two optoelectronic devices.
 10. The optoelectronic module ofclaim 9 further comprising a focus adjustment for said imager.
 11. A lowprofile connectorless board-to-board interconnect comprising: a firstcircuit board; a first optoelectronic module; said first optoelectronicmodule smaller than said first circuit board; said first optoelectronicmodule electrically connected to said first circuit board; said firstoptoelectronic module being physically mounted to said first circuitboard a second circuit board; a second optoelectronic module; saidsecond optoelectronic module smaller than said second circuit board;said second optoelectronic module electrically connected to said secondcircuit board; said second optoelectronic module being physicallymounted to said second circuit board; said first optoelectronic moduleand said second optoelectronic module being operatively opticallyconnected; said first optoelectronic module and said secondoptoelectronic module configured to optically transmit data between thesaid first circuit board and said second circuit board; at least one ofsaid first optoelectronic module and said second optoelectronic modulecomprising a catadioptric imager configured to provide a compact imagerand module.
 12. The low profile connectorless board-to-boardinterconnect of claim 11 wherein said electrical connection between saidfirst optoelectronic module and said first circuit board comprises aball grid array.
 13. The low profile connectorless board-to-boardinterconnect of claim 11 wherein said electrical connection between saidfirst optoelectronic module and said first circuit board comprises a pingrid array.
 14. A low profile connectorless board-to-board interconnectcomprising: a first circuit board; a first optoelectronic module; saidfirst optoelectronic module comprising a first imager; said firstoptoelectronic module mounted on said first circuit board; said firstoptoelectronic module comprising an object array; said object arraycomprising at least two optoelectronic devices; said object arrayfurther comprising at least one emitter or detector; said firstoptoelectronic module electrically connected to said first circuitboard; a second circuit board; a second optoelectronic module; saidsecond optoelectronic module comprising a second imager; said secondoptoelectronic module mounted on said second circuit board; said secondoptoelectronic module comprising an image array; said image arraycomprising at least two optoelectronic devices; said image array furthercomprising at least one emitter or detector; said second optoelectronicmodule electrically connected to said second circuit board; said firstoptoelectronic module and said second optoelectronic module beingoperatively optically connected; said first imager and said secondimager configured to image said object array onto said image array; saidfirst imager comprising a first catadioptric imager. wherein the saidfirst catadioptric imager is configured to reduce the distance betweenthe object array and the image array compared to the size of the arrays.15. The low profile connectorless board-to-board interconnect of claim14 wherein said second imager comprises a second catadioptric imager.16. The low profile connectorless board-to-board interconnect of claim15 wherein said first catadioptric imager and said second optoelectronicimager are configured to reduce the distance between the object arrayand the image array compared to the size of the arrays.
 17. The lowprofile connectorless board-to-board interconnect of claim 14 whereinthe said first catadioptric imager has an annular field.
 18. An annularoptoelectronic device array comprising: a die; said die comprising anarray of at least two optoelectronic devices comprising at least oneemitter or detector; said array of at least two optoelectronic devicesbeing located in a substantially annular region.
 19. The optoelectronicdevice array of claim 18 wherein the optoelectronic devices in saidarray of at least two optoelectronic devices comprise both at least oneemitter and at least one detector.
 20. The optoelectronic device arrayof claim 18 wherein the said die further comprises an integratedcircuit.
 21. The optoelectronic device array of claim 18 wherein thesaid array of at least two optoelectronic devices comprises at least oneVCSEL.